In physics, a famous paradox is hanging on by a fiber ...

Researchers from the Photonics team and the Cold Atoms team have just taken a step in understanding the paradox of the physical process where a complex system returns to its initial state instead of evolving towards equilibrium.

Résumé de l’article « En physique, un célèbre paradoxe qui ne tient qu’à une fibre… » publié par l’équipe Photonique dans The Conversation le 2 mai 2018. Imaginez une barre de métal chauffée à l’une de ses extrémités. Au lieu que la chaleur ne se répartisse peu à peu sur toute sa longueur, la barre finirait par redevenir brûlante à l’endroit d’origine. Il s’agit là d’un processus physique où un système complexe retourne à son état initial au lieu d’évoluer vers l’équilibre : l’explication de ce paradoxe résiste depuis plus de soixante ans aux physiciens. Grâce une série de mesures bien plus riches et complètes qu’auparavant, réalisées dans des fibres optiques, notre équipe franco-italienne vient de franchir un palier dans la compréhension fine de ce phénomène.

Abstract of the article « In physics, a famous paradox is hanging on by a fiber... » published by the Photonics team in The Conversation on May 2, 2018. Imagine a heated metal bar at one end. Instead of the heat gradually spreading over its entire length, the bar would eventually become hot again at the original place. This is a physical process where a complex system returns to its original state instead of evolving towards equilibrium: the explanation of this paradox has resisted with physicists for more than sixty years. Thanks to a series of measures more detailed and complete than before made in optical fibers, our Franco-Italian team has just taken a step in the fine understanding of this phenomenon.

The publication which relates its progress (Fibre multi-wave mixing combs reveal the broken symmetry of Fermi–Pasta–Ulam recurrence), did the cover of the magazine Nature Photonics Volume 12 n°5 May 2018.

These are leanding results for physics in general but it is also interesting for the public: the process in question is at the heart of phenomena as diverse as the formation of rogue waves in the ocean or the design of high precision optical clocks. Arnaud Mussot Professor at the PhLAM Laboratory

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The article of popularization "In physics, a famous paradox is hanging on by a fiber..." published in The Conversation May 2, 2018: © The original version of this article was published on The Conversation All rights reserved. > Link